Inkjet printing systems often utilize one or more replaceable ink containers that hold a finite volume of ink. An ink container can be refilled or replaced with a new container if the ink container is unable to deliver ink. Many known ink containers are unable to deliver all of the ink in the ink container and are considered to be effectively empty although some ink remains in the ink container. Such ink containers can be refilled or replaced when the ink container ceases to adequately deliver ink. Users generally prefer ink containers that do not have to be frequently refilled or replaced. Furthermore, users generally prefer ink containers that are relatively easy to refill or replace when necessary.